if you can wait untiil the end of the summer, you should check out anyplace that rents bikes. my former girlfriend (from when I lived in utah) got both her bikes from end of season rental sales, and when I moved to SC, I picked up a kona for a pretty good deal.
other than that, like Greg said, check the classifieds, there are plenty of used bikes out there. I don't think you can really go wrong with any bike, as long as it fits you and it has quality components. Def go for disk brakes, they are far superior to any rim brake.
Trek, specialized, diamond back, kona.....I don't even know all of the current mfg out there, but unless you are really hardcore racing, you can have a great bike from any of them.